Arc lamp



Jan. 2, 1951 W, Fl WE|SHE|T 2,536,242

ARC LAMP Filed Feb. 24, 1948 P .nw

|NVENTOK WMY F WExsHElr BY 514W/ ATTO RNEY.

Patented Jan. 2, 1951 ARC LAMP William Frederick Weisheit, Los Angeles, Calif.,

assgnor to Twentieth Century-Fox Film Corporation, Los Angeles, Calif., a corporation of New York Application February 24, 1948, Serial No. 10,279

Claims. l

This invention relates to arc lamps and deals principally with an improvement in the means for holding carbons in lamps of this character.

The principal object of the invention to be described hereinafter is to provide an improved means whereby carbon pencils may be quickly and easily mounted and securely held in a burning position in motion picture projectors'and the like.- That the invention will have usefulness in holding carbons in other types of arc lamps will be obvious to those skilled in the art.

In motion picture projection machines particularly, which employ arc lights for light sources, it is the common practice to use two carbon pencils, one a positive and one a negative, for forming an arc. The pencils are arranged to meet at a point which must be held within a fixed zone to meet the requirements of the optical system in the lamp, and in order to do this it is necessary to provide means whereby the carbon pencils may be moved relative to the Zone and to each other. Also, to those versed in this art it is known that these carbon pencils are more or less rapidly consumed and must be continually replaced. Oftentimes the replacement of the pencils must be done in a hurry to avoid interruption in the projection of a picture. My invention provides improvements in the means for mounting the positive carbon in arc lamps of the above character.

The invention may take the form of an additional element to the existing structure and may be incorporated with no change whatsoever in the structure, but in its preferred form requires a minor modification. The object of my invention is to provide a clamp for holding the positive carbon that will automatically supply a predetermined amount of pressure to hold the carbon pencil in the clamp. The pressure applied is of a, resilient nature so that there will be no loosening of pressure due to vibration and no excessive pressure causing breaking or cracking of the carbon. Accordingly, it becomes a specific object of this invention to provide a spring pressed means for clamping a carbon pencil Yin an arc light whereby the pencil is automatically held fixed with a predetermined amount of pressure, thus obviating breakage of the carbon and loosening of the clamp. The usual construction for holding carbons consists of a clamp, one side of which is moved by a screw threaded rod, similar to a vise. The rod in turn is operated by a handle; Accordingly, another object is to provide a helical, torsional spring which may be applied to automatically operate the clamping handle which ordinarily is manually operated to rotate the rod 2 and thus set the clamp for holding a carbon pencil.

The foregoing and other objects will become apparent as the description proceeds in conjunction with the drawing which shows the means for mounting the positive carbon pencil in a projection machine using` an arc lamp for a light source. Y

Referring more specifically to the drawing, it can be seen that'there are two carbon pencils, namely, the negative pencil II and the positive pencil I2. The vario-us other means for mounting the negative pencil and for moving the two pencils are not a part of this invention and consequently are neither shown nor described here. Since the invention deals with the means lfor mounting the positive pencil I2, only that part of the machine is shown which enters into the invention. Y

The means for mounting the pencil I2 takes the customary form of a bracket I3 mounted upon a traveling member I 4 which may be forced along a screw threaded member I5 in any conventional manner, which is not shown nor described here. The pencil I2 which is supported in the bracket I3 is clamped in the bracket by means of a movable shoe I6 that engages the pencil and forces it upwardly against the top of the bracket. The shoe I6 in turn is forced to move upwardly by a screw threaded rod I1 working in an internally screw threaded sleeve I8 which is a part of the bracket I3. The rod I'I is turned in the screw threaded sleeve I8 by means of a handle I9 which ordinarily is manually operated. Means are provided for adjusting the handle I9 on the rod I7 so that the operator may set it at the most convenient position for operation. This means takes the form of a clutch 2D which works into a block 2I that is fastened to the rod I1 by a pin 22. The.

handle I9 is pressed downwardly into the clutch by means of a screw threaded nut 23. The foregoing is the conventional way of mounting the carbon pencil I2 in the positive bracket. The outer end of the pencil I2 is supported on a standard 24 which supports the carbon in a position so that it will approach contact with the negative carbon II.

In ordinary practice the carbon pencil is mounted in the bracket and the operator brings pressure to bear on the pencil to hold it in the bracket by moving the handle I9 by hand. If the operator applies too much pressure, he cracks the carbon. If he applies too little pressure, the bracket works loose and the carbon, due to vibration of the machinery and its attendant andare the carbon in the bracket. The result is that all the operator needs to do With my invention is to press the handle back until the shoe I6 drops down and opens the clamp enough to slip in the pencil Upon releasevof the handle, the spring operates to turn the rod Il so that the pencil is clamped in position with predetermined uniform pressure. The device requires no further attention on the part of the operator. The spring brings the pressure to exactly the right amount, whereby the pencil is held securely without breaking and will not loosen under the conditions of operation- The operation is fast and sure and not only saves in the number of carbons that are saved from breakage but relieves the operator from any fear of having cracked the carbon whereby a sputtering may occur when the crack reaches the crater.

I claim:

1` Means' for holding carbon pencils in arc lampsy comprising opposed clamping members, means for moving one of said members relative to the other to engage and support a carbon pen,- cil, therebetween, said means including a screw threaded rod, and resilient means for rotating said rod to effect a clamping action between said ,clamping members.

lamps comprising opposed clamping members,

4 means for moving one of said members relative to the other, said means including a screw threaded rod and a torsion spring mounted on said rod arranged to rotate the same to effect a predetermined clamping action between said clamping members.

3. Means for holding carbon pencils in arc lamps comprising opposed clamping members, means for moving one of said members relative to the other, said means including a screw threaded rod, a handle on said rod for rotating the same to open said clamp, and a spring on said rod arranged to rotate the same to yieldingly close said clamp.

4. Means for holding carbon pencils in arc lamps comprising opposed clamping members, one of which is moved relative to the other by rotating a screw threaded rod, and means for yieldingly rotating said rod with a predetermined force.

5. Means for holding carbon pencils irl-"aro lamps comprising opposed clamping members', a screw threaded rod for moving one of said members relative to the other, and a torsion vspring mounted on said rod to exert a predetermined force to yieldingly rotate the same to effect a controlled clamping action between said clamping members.

WILLIAM FREDERICK WEISHEITQ REFERENCES. CITED The following references areof record inthe file of this patent:

UNITED STATES PATENTS Number Name Date Y 21,182,895 Clay May 16, 1916 2,269,771 Raymond Jan. 13, '1942 2,427,922 Klamm Sept. 23,r 19e?? 

